id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
18436	[PATCH RFC] There should be a method to know when a DataSet's DataSources change	taylor.smock	team	"In the attached patch, I've created a new listener that the DataSet triggers when it modifies the DataSource list.

Possible use cases:
* Mapillary
* Microsoft Streetside (''the interesting code is literally the same as Mapillary's'')
* OpenStreetCam
* MapWithAI

Mapillary currently uses the following in `src/main/java/org/openstreetmap/josm/plugins/mapillary/MapillaryLayer.java`:
{{{
#!java
    new DataSetListenerAdapter(e -> {
      if (e instanceof DataChangedEvent && MapillaryDownloader.getMode() == DOWNLOAD_MODE.OSM_AREA) {
        // When more data is downloaded, a delayed update is thrown, in order to
        // wait for the data bounds to be set.
        MainApplication.worker.execute(MapillaryDownloader::downloadOSMArea);
      }
    });
}}}

While it works, it is prone to being called when the user didn't download an additional area."	enhancement	closed	normal	19.12	Core		fixed	datasource, download